Digital subscriber line (DSL) and T1/E1 chassis are used in telecommunication systems. One function of a DSL chassis is to interface ports and a function of a T1/E1 chassis is to interface T1/E1 ports. The same chassis can support either DSL or T1/E1 ports depending upon line cards used. The chassis includes a backplane. The backplane is adapted to deliver power to and provide high speed interconnections between, line cards, multiplexer cards and a management card. The line cards, multiplexer cards and management card are all adapted to plug into the backplane of the chassis. Line cards (or modules) are printed circuit boards that provide operational functions for designated phone lines or telephones in a telephone system.
The receive input of a DSX-1 line needs to be coupled across a termination resistor of a select value. One typical method of achieving this is by placing the termination resistor on the backplane. However, this limits the ability of using the same slot in the backplane for other purposes that don't require the use of a termination resistor. For example, in a situation where DSL ports are designed to not require termination for any loop. This would create a contradiction of having a termination for the DSX-1 ports but not for the DSL ports in the same chassis. Accordingly, it is desired in the art to have a chassis and line card combination that does not require a termination resistor on the backplane. Moreover, it is desired in the art to have a line card that is designed to work in both a chassis that has a backplane with a termination resistor and a chassis having a backplane without a termination resistor.
For the reasons stated above and for other reasons stated below which will become apparent to those skilled in the art upon reading and understanding the present specification, there is a need in the art for an improved line card and chassis system.